Conformational equilibria of the L-iduronate residue in non-sulphated di-, tetra- and hexa-saccharides and their alditols derived from dermatan sulphate.
The conformation of the L-iduronate residue in non-sulphated di-, tetra- and hexa-saccharides and their alditol derivatives derived from rooster comb dermatan sulphate was investigated by 400 MHz 1H-n.m.r. spectroscopy. The ratio of conformational isomers is obtained by the average spin-spin coupling constants of a mixture of nearly isoenergetic conformers (1C4, 4C1 and 2S0). The non-reducing terminal L-iduronate residue in the tetrasaccharides (I-H-I-H and I-H-G-H) and their alditols (I-H-I-H-ol and I-H-G-H-ol) is in equilibrium with three conformers (1C4, 30%; 4C1, 40%; 2S0, 30%) of nearly equal population. Whereas the internal L-iduronate residue in the tetrasaccharides (I-H-I-H and G-H-I-H) exists as an equilibrium mixture of 1C4 (54%) and 2S0 (42-44%) conformers, that of their alditols (I-H-I-H-ol and G-H-I-H-ol) is in equilibrium between 2S0 conformer (66%) and 1C4 conformer (28%). The conformational population for the internal L-iduronate residue 2I in the hexasaccharide (3I-H-2I-H-1I-H) is also calculated and compared with that for the L-iduronate residue in native dermatan sulphate, which was calculated on the basis of the spin-spin coupling constants reported by Gatti, Casu, Torri & Vercellotti [(1979) Carbohydr. Res. 68, c3-c7].
Inoue
Y
Y
School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
Inouye
Y
Y
Nagasawa
K
K
D000818:Animals; D002236:Carbohydrate Conformation; D002645:Chickens; D002807:Chondroitin / Q000031:analogs & derivatives; D003129:Comb and Wattles; D003871:Dermatan Sulfate; D007067:Iduronic Acid; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009844:Oligosaccharides; D013402:Sugar Alcohols; D014574:Uronic Acids
D009844:Oligosaccharides; D013402:Sugar Alcohols; D014574:Uronic Acids; D003871:Dermatan Sulfate; D007067:Iduronic Acid; D002807:Chondroitin